Bleeding
on Probing
Defined

A key element in periodontal risk assessment,
bleeding on probing is most accurate when used
in conjunction with other disease indicators.
By Wayne A. Aldredge, DMD

EDUCATIONAL OBJECTIVES

After reading this course, the participant should
be able to:

Discuss the role of bleeding on probing (BOP) in periodontal
disease risk assessment.
1. Explain the efficacy of BOP as a periodontal disease indicator.
2. Identify different systems of assessing gingival health.
3. Detail the effects of dental biofilm on BOP.

INTRODUCTION

As our careers unfold and our experience in dental practice grows, it is important to regularly re-examine the basics and make sure
our clinical practice is evidence-based and current. Probing periodontal pockets and recording the subsequent bleeding (or lack
thereof) is one of the mainstays of periodontal management. This article, "Bleeding on Probing Defined," will help ensure that the
conclusions made from clinical bleeding on probing data are based on up-to-date scientific knowledge. The Colgate-Palmolive Company
is delighted to have provided an unrestricted educational grant to support the second article of this four part series "Partnering to
Improve Periodontal Health" in collaboration with the American Academy of Periodontology.—Barbara Shearer, BDS, MDS, PhD, Director of Scientific Affairs, Colgate Oral Pharmaceuticals

TRADITIONALLY, BLEEDING ON PROBING (BOP) HAS BEEN USED
TO DIAGNOSE THE PRESENCE OF PERIODONTAL DISEASES, AND
IT IS A RELIABLE INDICATOR OF GINGIVAL INFLAMMATION,
especially when used in conjunction with other factors. Many
believe that BOP also serves as an indicator of future clinical
attachment loss, however, the evidence supporting this correlation
is weak.1

BOP can be effective in the diagnosis and monitoring of active
periodontal diseases,2,3 but when used as a stand-alone test, it
can be inaccurate.3 BOP is not a definitive sign of periodontal
diseases, as there are other factors besides gingival inflammation
that can cause capillary fragility, and a comprehensive patient
evaluation must be performed. A proper diagnosis should
include a combination of BOP, probing depth, and clinical
attachment loss. Assessments must include an evaluation of medical
history, medication usage, physical disabilities, and systemic
factors. Full-mouth radiographs can help clinicians estimate the
amount of remaining alveolar bone, as well as provide valuable
reference points for future assessments.

BOP is useful for predicting the progression of periodontitis,
and pockets that bleed on two or three consecutive appointments
are likely to become active.4 Sites that bleed on probing
tend to have significantly more inflammation than nonbleeding sites.5 But the information collected during probing can be
affected by a number of variables, including choice of probe,
probing reproducibility, probe angulation, force used, site location,
and gingival health status.

Figure 1. Example of bleeding on probing.

Figure 2. Scaling and root planing is one of the most effective ways to
remove biofilm. Figure 2A (top) shows a patient before receiving scaling
and root planing. Figure 2B (bottom) is the patient 13 months later, after
receiving regular periodontal treatment, including scaling and root planing
and osseous surgery.

PROBING EFFICACY

Information collected through periodontal probing can be
used to monitor pocket depth, bone loss, and attachment loss.
It is useful in providing either positive predictive values or negative
predictive values that illustrate disease progression. Predictive
values are measurements used to interpret diagnostic
test results.

A positive predictive value indicates the percentage of people
who both exhibit BOP and are correctly diagnosed with progressive
periodontal diseases. A negative predictive value indicates
the percentage of people whose BOP test results show no
bleeding and no active disease progression. These values do not
diagnose periodontal disease, but they do indicate a patient's
likelihood of developing disease in the future.

Clinical studies support the relevance of BOP in predicting the
course of oral periodontal diseases,6 and they show the absence
of BOP to be a reliable indicator of periodontal stability.

ASSESSING BLEEDING ON PROBING

Most clinicians use calibrated periodontal probes to assess BOP,
but wooden interdental cleaners and dental floss are also utilized.
Calibrated periodontal probes measure probing depth or the distance
from the gingival margin to the base of the probeable
crevice, and the clinical attachment loss—the distance from the
cemento-enamel junction to the base of the probeable crevice
(Figure 1). These measurements provide an approximation of
periodontal pocket depth and are invaluable as reference points
for monitoring disease progression.

Periodontal pockets are clinically important because they
provide a habitat for periodontal pathogens. Deep pockets
can be difficult for both the clinician and patient to clean,
and they are more likely to harbor harmful periodontal pathogenic
bacteria.

There are several gingival assessment systems used to quantify
BOP. Each method can produce different results. Most gingival
bleeding occurs during or immediately after probing, but some
indices incorporate a time factor to allow for bleeding to begin.7
Other indices require the amount of gingival bleeding to be
assessed.8 BOP may also increase if the patient has performed oral
hygiene procedures just before being examined.9 Table 1 provides
a description of the most popular gingival assessment systems.8, 10–13

Table 1. Gingival Assessment Systems

Gingival Index
One of the most popular systems, the Gingival Index—introduced in 1963 by
Loe and Silness—is based on inserting the probe apically to the gingival
margin.10 It is generally used to assess the severity of gingivitis based on
bleeding on probing (BOP). The tooth is examined on the lingual, mesial,
distal, and buccal surfaces, and probed to test the degree of firmness.
Numbers are used to evaluate the degree of inflammation, with a value of 0
given to normal gingiva; 1 for mild inflammation but no BOP; 2 for moderate
inflammation and BOP; and 3 for gingiva exhibiting severe inflammation with
a tendency to bleed spontaneously.

Papilla Bleeding Index
The Papilla Bleeding Index is based on sweeping a probe in the sulcus from
the line angle to the interproximal contact.12

Papillary Bleeding Score
In 1979, the Papillary Bleeding Score was introduced by Loesche.8 It uses a
triangular-shaped wooden toothpick to stimulate the interproximal gingival
tissue—inspecting one quadrant at a time. A value of 0 is given to healthy
gingival tissue; 1 for red tissue with no bleeding; 2 for bleeding without flow
along the gingival margin; 3 for bleeding with flow along the gingival
margin; 4 for copious amounts of bleeding; and 5 for severely inflamed
tissue that has a tendency to spontaneously bleed.

Plaque Index
The Plaque Index was developed by Silness and Loe to assess the thickness of
plaque at the cervical margin. This index requires that each tooth be dried
and examined with an explorer passed over the distal, mesial, lingual, and
buccal surfaces. Each surface is given a score between 0 and 3. A 0 indicates
no plaque; 1 indicates nonvisible plaque that can only be detected by
scraping with a probe; 2 indicates visible plaque; and 3 indicates abundant
plaque. The scores for the individual surfaces of each tooth are then added
up and divided by the number of sites assessed. Increased plaque build-up
leads to increased BOP.

Ramfjord Teeth
Ramfjord Teeth (numbers 3, 9, 12, 19, 25, and 28) are used to assess the
condition of the whole mouth. This type of partial-mouth assessment is an
acceptable alternative to full-mouth examinations for epidemiologic studies of gingivitis, but is inadequate for epidemiologic studies of periodontitis.13

VARIABLES THAT AFFECT BLEEDING ON PROBING

Bleeding can be more prevalent if a site is continually probed,
but one of the most important variables is the force used when
probing. If excessive force or incorrect technique is used, even
healthy tissue may begin bleeding.14 Bleeding is also more likely
to occur if the gingival tissue is thinner than normal.15

The accuracy of probing measurements also depends on the
force used, the shape and size of the probe tip, and the level of
inflammation in the tissues. In clinically healthy sites, the tissues
are more toned and tend to have a "hammock" effect, so when
a gentle insertion force is used, a probe is less likely to penetrate
to the apical termination of the junctional epithelium. Studies
have shown that when a force greater than 25 g is applied, bleeding
at healthy sites can be induced.16

When untreated, diseased sites are probed, the probe tends to
penetrate more deeply, which leads to overestimated probing measurements.
On the other hand, post-treatment measurements tend
to be underestimated, although the discrepancy is usually no more
than a millimeter. Studies have shown that the probe with a diameter
of 0.63 mm produces the most accurate results,17 as smaller
probes often penetrate beyond the base of the pocket into the
inflamed connective tissue. In heavily inflamed tissues, a probe can
penetrate up to 1 mm into the connective tissue attachment.18

Higher probing forces are thought to traumatize tissues, cause
bleeding, and lead to a false assumption of inflammation.19
Although higher probing forces lead to more reproducible readings,
the use of lighter forces makes it easier to detect smaller
changes in attachment levels. Clinicians tend to use greater force
in posterior segments than in anterior segments.

PROBING REPRODUCIBILITY

One of the most important factors for collecting accurate results
is probing reproducibility. A study that compared two probes set
at 0.75 N found no differences in reproducibility,20 while another
study looked at intra-examiner and inter-examiner reproducibility
for threshold probing depths of greater than 1 mm and found an
accuracy rate of 91.3%.21 The introduction of controlled-force
probes has decreased much of the reproducibility error, but mistakes
in manufacturing can still affect measurements.

Tests have shown that the accuracy of probe markings can
vary considerably from the manufacturer's designated calibration.
22 Probing depths can be affected by whether a
tapered probe or a parallel-sided probe is used, with the parallel
probe tending to result in deeper probing depths.23
However, when both types were compared, 89% of the results
showed no difference.

THE ROLE OF BIOFILM IN BLEEDING ON PROBING

Gingivitis is caused by an overgrowth of indigenous microflora,
which is both Gram negative and Gram positive. As the condition
develops, the prevalence of Gram-negative Actinomyces
species increases. Three species of Gram-negative and anaerobic
or facultative bacteria are the main etiologic agents responsible
for periodontal diseases.24Bacteroides forsythus, Porphyromonas gingivalis,
and Treponema denticola are most prevalent in clinical measures
of periodontal diseases. About 25% of plaque will become
Gram negative.

The process begins with glycoproteins from saliva binding to
the surface of the enamel forming the pellicle. The first bacteria
to attach to the pellicle are Gram-positive aerobic bacteria. After
a few days, anaerobic Gram-negative species begin to colonize
the biofilm, inducing an inflammatory response, while the biofilm
itself is a constantly renewing source of lipopolysaccharides (LPS).

Bacterial LPS are one of the major components of Gram-negative
bacteria surface membranes, and they promote a strong
immune response. Among individuals at risk of periodontitis,
the biofilm will enter the gingival sulcus, disrupting the union
between the coronal portion of the junctional epithelium (JE)
and the tooth. As the JE is converted into pocket epithelium, a
shallow gingival pocket is created that allows greater access for
substances, such as bacterial LPS, to blood vessels and the connective
tissues. Subgingival plaque is difficult to remove effectively
through brushing, flossing, or mouthrinses. The most
effective way to remove biofilm is through periodontal debridement
(Figure 2A and Figure 2B).

RISK FACTORS THAT AFFECT PERIODONTAL THERAPY

Gingival bleeding can also be symptomatic of systemic issues,
and unless these are treated correctly, periodontal therapy may not be sufficient to restore oral health. Systemic diseases,
the use of over-the-counter or prescribed medications,
and smoking can all affect periodontal health.

Smokers may exhibit less BOP because nicotine can suppress
bleeding, causing vasoconstriction in peripheral blood vessels
that can lead to a compromised immune response. An initial
study showed a significant correlation between tobacco usage
and gingivitis.25 In 1986, a study introduced experimental gingivitis
to a group of dental students, half of whom were smokers.
26 Although plaque formation rates were similar for both
groups, the smokers exhibited a less pronounced inflammatory response. These findings were backed up in a study in 1990,27 which supports the theory
that smokers have a reduced capacity to mount a defense against biofilm.

The presence of periodontitis can make it more difficult to control diabetes, and
people with diabetes are more susceptible to periodontitis. Patients with diabetes
undergoing periodontal therapy may end up needing less insulin,28 however, this
isn't always certain. The need for insulin may fluctuate because many patients start
taking a greater interest in their health after undergoing periodontal treatment, and
thus may become more compliant with their diabetes management regimen.

Patients taking anticoagulant agents, such as warfarin or heparin, that retard
clotting may sometimes experience increased gingival bleeding. Individuals taking
antiplatelet drugs following cardiac surgery are also at increased risk of prolonged
and spontaneous gingival bleeding. Patients taking aspirin and nonsteroidal antiinflammatory
drugs may experience increased blood loss if they are taken prior to
periodontal surgery. Ibuprofen has been found to significantly increase intraoperative
blood loss.29

TAKING ACTION

BOP is just one piece of the periodontal disease diagnosis puzzle. When BOP is the only
symptom exhibited, getting patients to view their oral health as at risk can be difficult.
Many patients feel that if they are not in pain, then nothing is wrong. Dental hygienists
are well-suited to explain the role that BOP plays in patients' oral health and encourage
them to take action. Dental hygienists must not only convince patients of the existence
and seriousness of their condition, but they need to also demonstrate how patients' oral
health will be affected in the future if appropriate action isn't taken.

Wayne A. Aldredge, DMD, is a clinical assistant professor in the
Department of Periodontics and Implantology at Stony Brook University
in Stony Brook, NY. He is also a diplomate of the American Board
of Periodontology. Aldredge maintains private periodontal practices
in both Holmdel and Nutley, NJ.